Method of manufacturing organic electroluminescence display device and electronic equipment including organic electroluminescence display device manufactured by the manufacturing method

ABSTRACT

Provided is a method of manufacturing an organic electroluminescence display device including an organic electroluminescence element, which has element characteristics comparable to those in the case of a vacuum in-situ process, while utilizing a patterning approach based on photolithography. The method of manufacturing an organic electroluminescence display device includes: an organic compound layer-forming step of forming an organic compound layer at least on a first electrode; a release layer-forming step of forming a release layer on the organic compound layer; a release layer-processing step of processing the release layer; and an organic compound layer-processing step of removing the organic compound layer in a region not covered with the release layer processed in the release layer-processing step, and at least the lowermost layer out of the release layer is a deposited film formed of a material soluble in a polar solvent.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method of manufacturing an organicelectroluminescence (EL) display device and an electronic equipmentincluding an organic EL display device manufactured by the manufacturingmethod.

2. Description of the Related Art

A generally known display device having organic EL elements mountedthereon is a device in which pixels each having a single or multipleorganic EL elements are arranged in a predetermined pattern. By thosepixels, a display region of the display device is two-dimensionally andfinely divided. The organic EL elements included in the pixels areelectronic elements which output, for example, any one of red light,green light, and blue light. A display device having organic EL elementsmounted thereon obtains a full-color image by driving the organic ELelements for outputting desired colors at desired emission intensities.

By the way, in an organic EL element which is a component of a displaydevice, an organic compound layer in the element is a thin film layerformed by forming a thin film made of an organic material by vapordeposition or the like. When the organic compound layer in the organicEL element of the display device is formed for each element by vapordeposition, a fine patterning technology is necessary. Upon performanceof the patterning, a fine metal mask the fineness of which is accordingto the fineness of the patterning is necessary. However, a vapordeposited film which adheres when the metal mask is used repeatedly invapor deposition may narrow an opening in the mask or stress may deformthe opening in the mask. Therefore, it is necessary to clean the maskused after film formation for a fixed number of times, which is adisadvantageous factor from the viewpoint of manufacturing costs.Further, partly due to a limitation on the process accuracy of the mask,the pixel size has a limit of about 100 μm, which is disadvantageous toa finer size. Further, with regard to the substrate size, when a finemetal mask is increased in size, in order to secure the positionalaccuracy of the opening in the mask, it is necessary to enhance thestiffness of a frame of the mask. However, when the stiffness of themask is enhanced, an increase in the weight of the mask itself is causedaccordingly. Therefore, from the viewpoint of both processability andhandling, when large format display devices of the fourth and subsequentgenerations are to be produced, an optimum production process of a fineorganic EL element and a display device having the organic EL elementmounted thereon has not taken shape at present.

Under those circumstances, a method of producing a display device havinga fine organic EL element without using a metal mask is proposed.

In the method proposed in Japanese Patent No. 3839276, a photoresist isdirectly formed on an emission layer. When the method is adopted, thephotoresist to be used generally contains large amounts of aphotoinitiator, a crosslinking agent, and the like. Here, thephotoinitiator, the crosslinking agent, and the like are each a materialfor changing insolubility at least in a developer. In the methodproposed in Japanese Patent No. 4507759, an intermediate layer formed ofa water-soluble material is provided on an organic compound layer, andthe organic compound layer is patterned by performing photolithographyon the intermediate layer. Here, a water-soluble polymer forconstituting the intermediate layer to be formed on an emission layer isgenerally insulative. In addition, Japanese Patent No. 4544811 proposessuch a technology that a water-soluble polymer is used as a releaselayer and a photoresist is released together with the release layer.

The resist, the intermediate layer, the release layer, and the like aregenerally insulative. Accordingly, when any one of those layers is beingleft on the surface of the emission layer or the like of an organic ELelement, the layer serves as a resistance to remarkably deteriorate theelement characteristics of the organic EL element. Accordingly, theresist, the intermediate layer, the release layer, and the like need tobe removed so that none of the layers may remain on the surface of theemission layer or the like. However, it is difficult to completelyremove the resist, the intermediate layer, the release layer, and thelike each formed of a polymer material, and hence the residue thatcannot be completely removed remains in the device to some extent.Further, concern is raised about the deterioration of the elementcharacteristics due to, for example, the following. A trace amount of animpurity in the resist, the intermediate layer, the release layer, orthe like, or a solvent to be used upon application of the resist, theintermediate layer, the release layer, or the like diffuses to theemission layer or the like constituting the organic compound layer tocause the crystallization of the organic compound layer. Accordingly,the following problem has conventionally arisen. The elementcharacteristics of an organic EL element in an organic EL display deviceproduced by patterning involving utilizing a photolithography processare inferior to the element characteristics of organic EL elementsformed like a pattern with a metal mask or the like in a vacuum in-situfashion.

SUMMARY OF THE INVENTION

The present invention has been made to solve the problems, and an objectof the present invention is to provide a method of manufacturing anorganic EL display device including an organic EL element, which haselement characteristics comparable to those of an organic EL elementformed with a metal mask or the like in a vacuum in-situ fashion, whileutilizing a patterning approach based on photolithography.

The method of manufacturing an organic EL display device of the presentinvention is a method of manufacturing an organic EL display devicehaving an organic EL element including a first electrode and a secondelectrode, and an organic compound layer arranged between the firstelectrode and the second electrode, the organic compound layer beingpatterned into a desired shape, the method including: an organiccompound layer-forming step of forming the organic compound layer atleast on the first electrode; a release layer-forming step of forming arelease layer on the organic compound layer; a release layer-processingstep of processing the release layer into the desired shape; an organiccompound layer-processing step of removing the organic compound layer ina region not covered with the release layer processed in the releaselayer-processing step; and a release layer-removing step, in which atleast a lowermost layer of the release layer is a deposited film formedof a material soluble in a polar solvent.

According to the present invention, there can be provided a method ofmanufacturing an organic EL display device including an organic ELelement, which has element characteristics comparable to those of anorganic EL element formed with a metal mask or the like in a vacuumin-situ fashion, while utilizing a patterning approach based onphotolithography.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic sectional view illustrating an example of anorganic EL display device to be manufactured by a manufacturing methodof the present invention.

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, 2G, 2H, 2I, 2J, 2K, 2L, 2M, 2N, and 2O areeach a schematic sectional view illustrating Embodiment 1 in the methodof manufacturing an organic EL display device of the present invention.

FIG. 3 is a graph illustrating thickness changes in a compound 1 and acompound A2 over an etching time.

FIG. 4 is a graph illustrating the solubilities of a predeterminedaromatic hydrocarbon compound and a predetermined heterocyclic compoundin an aqueous solution of isopropyl alcohol.

FIGS. 5A, 5B, 5C, 5D, and 5E are each a schematic sectional viewillustrating Embodiment 2 in the method of manufacturing an organic ELdisplay device of the present invention.

FIGS. 6A, 6B, 6C, 6D, 6E, and 6F are each a schematic sectional viewillustrating Embodiment 3 in the method of manufacturing an organic ELdisplay device of the present invention.

FIG. 7 is a block diagram of a digital camera system using an organic ELdisplay device formed by the method of manufacturing an organic ELdisplay device of the present invention.

DESCRIPTION OF THE EMBODIMENTS

A method of manufacturing an organic EL display device of the presentinvention is a method of manufacturing an organic EL display devicehaving an organic EL element including a first electrode and a secondelectrode, and an organic compound layer arranged between the firstelectrode and the second electrode, the organic compound layer beingpatterned into a desired shape.

The manufacturing method of the present invention includes at least thefollowing steps (A) to (E):

(A) an organic compound layer-forming step of forming the organiccompound layer on the first electrode;(B) a release layer-forming step of forming a release layer on theorganic compound layer;(C) a release layer-processing step of processing the release layer intoa desired shape;(D) an organic compound layer-processing step of removing the organiccompound layer in a region not covered with the release layer processedin the release layer-processing step; and(E) the step of removing the release layer with a polar solvent.

In addition, in the present invention, at least the lowermost layer ofthe release layer is a deposited film soluble in the polar solvent.Further, as a preferred mode in the present invention, the step offorming a layer containing an alkali metal component on the organiccompound layer is further included after the step (E).

Hereinafter, an embodiment of the present invention is described withreference to drawings. It should be noted that in the followingdescription, a well-known technology or known technology in thetechnical field is applicable to a portion not specifically illustratedor described. In addition, embodiments to be described below are eachmerely one embodiment of the present invention, and the presentinvention is not limited thereto. In addition, the embodiments to bedescribed below may be appropriately combined as long as the combinationdoes not deviate from the gist of the present invention.

Embodiment 1

(Organic EL Display Device)

FIG. 1 is a schematic sectional view illustrating an example of anorganic EL display device to be manufactured by the manufacturing methodof the present invention. An organic EL display device 1 of FIG. 1 hasthree kinds of sub-pixels, that is, a first sub-pixel 20 a, a secondsub-pixel 20 b, and a third sub-pixel 20 c provided on a supportingsubstrate 10. Here, a pixel is constituted of the first sub-pixel 20 a,the second sub-pixel 20 b, and the third sub-pixel 20 c. Although onepixel formed of the first sub-pixel 20 a, the second sub-pixel 20 b, andthe third sub-pixel 20 c is illustrated in the organic EL display device1 of FIG. 1, multiple pixels are placed in a matrix fashion on thesupporting substrate 10 in an actual organic EL display device.

In addition, in the organic EL display device 1 of FIG. 1, eachsub-pixel (20 a, 20 b, or 20 c) has a first electrode 21 (21 a, 21 b, 21c), an organic compound layer 22 (22 a, 22 b, 22 c), a chargeinjection/transport layer 23, and a second electrode 24.

The first electrode 21 a, 21 b, or 21 c is electrode layer (lowerelectrode) provided on the supporting substrate 10, and is separatelyprovided for each sub-pixel. In addition, the first electrodes 21 a, 21b, and 21 c are each electrically connected to a switching element (notshown) such as a TFT.

The organic compound layer 22 a, 22 b, or 22 c is single layer formed ofa predetermined organic compound or a laminate formed of multiple layersof such kind. It should be noted that the organic compound layer 22 a,22 b, or 22 c has at least an emission layer (not shown) for outputtinglight of any one of the colors including a red color, a green color, anda blue color.

The charge injection/transport layer 23 is provided for injecting ortransporting a hole or electron injected from the second electrode 24into the organic compound layer 22. Although the chargeinjection/transport layer 23 is provided as a layer common to therespective sub-pixels (20 a, 20 b, and 20 c) in the organic EL displaydevice 1 of FIG. 1, the present invention is not limited thereto. Inother words, the charge injection/transport layer 23 may be separatelyprovided for each sub-pixel.

Although the second electrode 24 (upper electrode) is provided as alayer common to the respective sub-pixels (20 a, 20 b, and 20 c) as inthe charge injection/transport layer 23 in the organic EL display device1 of FIG. 1, the present invention is not limited thereto. In otherwords, the second electrode 24 may be separately provided for eachsub-pixel.

(Method of Manufacturing Organic EL Display Device)

Next, a method of manufacturing an organic EL display device includingthree kinds of sub-pixels for displaying colors different from oneanother is described as a specific example of the method ofmanufacturing an organic EL display device of FIG. 1 according to thepresent invention.

As described above, the method of manufacturing an organic EL displaydevice of the present invention includes at least the following steps(A) to (E):

(A) an organic compound layer-forming step of forming an organiccompound layer on a first electrode;(B) a release layer-forming step of forming a release layer on theorganic compound layer;(C) a release layer-processing step of processing the release layer intoa desired shape;(D) an organic compound layer-processing step of removing the organiccompound layer in a region not covered with the release layer processedin the release layer-processing step for the release layer; and(E) a step of removing the release layer with a polar solvent.

FIGS. 2A to 2O are each a schematic sectional view illustrating anexample of a manufacturing process for the organic EL display device ofFIG. 1. FIGS. 2A to 2O are each also a schematic sectional viewillustrating Embodiment 1 in the method of manufacturing an organic ELdisplay device of the present invention. Upon manufacture of the organicEL display device of FIG. 1, the organic EL display device ismanufactured by, for example, the following steps:

(1) the step of forming the first electrode (FIG. 2A);(2) the step of forming the organic compound layer (FIG. 2B);(3) the step of forming the release layer (FIG. 2C);(4) the step of forming a photosensitive resin layer (FIG. 2D);(5) the step of processing the photosensitive resin layer (FIG. 2E);(6) the step of processing the release layer (FIG. 2F);(7) the step of processing the organic compound layer (FIG. 2G);(8) the step of removing the photosensitive resin layer (FIG. 2L);(9) the step of removing the release layer (step of forming the chargetransport layer) (FIG. 2M);(10) the step of forming the charge injection/transport layer (FIG. 2N);and(11) the step of forming the second electrode (FIG. 20).

It should be noted that the steps (1) to (11) are merely specificexamples, and the present invention is not limited to the mode. As theorganic EL display device 1 of FIG. 1 requires the production of each ofthe three kinds of sub-pixels 20 a, 20 b, and 20 c having differentluminescent colors, the steps (2) to (7) need to be performed a total ofthree times after the performance of the step (1) before the performanceof the step (8). For example, first, the organic compound layer 22 a inthe first sub-pixel 20 a is formed by the steps (2) to (7) (FIG. 2G).Then, the organic compound layer 22 b in the second sub-pixel 20 b isformed by the steps (2) to (7) (FIG. 2H to FIG. 21). After that, theorganic compound layer 22 c in the third sub-pixel 20 c is formed by thesteps (2) to (7) (FIG. 2J to FIG. 2K).

Next, each of the steps (1) to (11) is specifically described.

(Step of Forming First Electrode)

First, the first electrodes 21 a, 21 b, and 21 c are formed on thesupporting substrate 10. A known substrate such as a glass substrate canbe selected as the supporting substrate 10. The first electrodes 21 a,21 b, and 21 c are electrode layers each formed of a known electrodematerial, and the constituent material is appropriately selected incorrespondence with a light extraction direction. When a top emissiontype organic EL display device is produced, the first electrodes 21 a,21 b, and 21 c are reflecting electrodes, and the second electrode 24 tobe described later is a light transmissive electrode. On the other hand,when a bottom emission type organic EL display device is produced, thefirst electrodes 21 a, 21 b, and 21 c are light transmissive electrodes,and the second electrode 24 is a reflecting electrode.

When the first electrodes 21 a, 21 b, and 21 c are formed as reflectingelectrodes, the constituent material for each of the first electrodes 21a, 21 b, and 21 c is preferably a metal material such as Cr, Al, Ag, Au,or Pt. Of those metal materials, a material having a high reflectance ismore preferred because the material can additionally improve lightextraction efficiency. A reflecting electrode is separately formed foreach sub-pixel by, for example, forming a thin film of the metalmaterial by a known method such as sputtering and processing the thinfilm into a desired shape by means of photolithography or the like. Itshould be noted that a layer formed of an oxide semiconductor havinglight-transmitting property such as ITO or IZO may be further providedon the thin film formed of any such metal material by reason of, forexample, the protection of the thin film or the regulation of a workfunction. Vapor deposition with a metal mask may also be utilized uponformation of the first electrodes 21 a, 21 b, and 21 c. Even when thevapor deposition with a metal mask is performed, the first electrode 21a, 21 b, or 21 c is separately formed for each sub-pixel.

When the first electrodes 21 a, 21 b, and 21 c are formed as lighttransmissive electrodes, examples of the constituent material for eachof the first electrodes 21 a, 21 b, and 21 c include oxidesemiconductors having light-transmitting properties such as indium tinoxide (ITO) and indium zinc oxide.

(Step of Forming Organic Compound Layer)

The organic compound layer 22 (22 a, 22 b, or 22 c) is a constituentmember for the organic EL display device, and is a single layer, or alaminate formed of multiple layers, including at least an emissionlayer. A layer except the emission layer in the organic compound layer22 is, for example, a hole injection layer, a hole transport layer, anelectron blocking layer, a hole blocking layer, an electron transportlayer, or an electron injection layer, provided that the presentinvention is not limited thereto. Here, a layer contacting the emissionlayer may be a charge transport layer (a hole transport layer or anelectron transport layer), or may be a charge blocking layer (anelectron blocking layer or a hole blocking layer).

In addition, a specific constitution of the organic compound layer 22with respect to the first electrode 21 has only to be appropriately setin accordance with the kind of carrier to be injected from the firstelectrode 21 toward the organic compound layer 22. That is, when a holeis injected from the first electrode 21, while a layer for injecting ortransporting a hole (a hole injection layer or a hole transport layer)is provided on the side of the first electrode 21, a layer for injectingor transporting an electron (an electron injection layer or an electrontransport layer) is provided on the side of the second electrode 24. Onthe other hand, when an electron is injected from the first electrode21, while a layer for injecting or transporting an electron (an electroninjection layer or an electron transport layer) is provided on the sideof the first electrode 21, a layer for injecting or transporting a hole(a hole injection layer or a hole transport layer) is provided on theside of the second electrode 24.

It should be noted that the organic compound layer 22 is preferably anamorphous film from the viewpoint of luminous efficiency. In addition,the thickness of each organic layer is preferably designed depending ona luminous wavelength in a proper fashion so that an opticalinterference effect may be obtained.

When one, or each of both, of a hole injection layer and a holetransport layer is provided, a hole-injectable/transportable material asa constituent material for the hole injection layer or the holetransport layer is not particularly limited, but a material having awork function at least smaller than that of a constituent material forthe emission layer and having high hole-transporting property ispreferably used. In addition, the hole injection layer or the holetransport layer may be provided with a function of blocking an electronflowing from the emission layer as well as a function of transporting ahole. Alternatively, separately from the hole injection layer or thehole transport layer, a layer having a function of blocking an electronflowing from the emission layer (electron blocking layer) may beinserted between the hole transport layer (or the hole injection layer)and the emission layer.

For example, an arylamine derivative, a stilbene derivative, apolyarylene, a condensed polycyclic hydrocarbon compound, a heterocyclicaromatic compound, a heterocyclic condensed polycyclic compound, and anorganometallic complex compound, and homooligomers and heterooligomersthereof can each be used as an organic luminescence material of eachcolor (red color/green color/blue color) in the emission layer, providedthat the luminescence material in the present invention is not limitedto the materials.

It should be noted that the luminescent colors of the emission layers inthe three kinds of organic compound layers 22 a, 22 b, and 22 c providedfor the lower electrodes 21 a, 21 b, and 21 c, respectively uponmanufacture of the organic EL display device of FIG. 1 are a blue color,a red color, and a green color, respectively, i.e., the luminescentcolors are different from one another. In addition, a combination of theluminescent colors is not particularly limited.

A constituent material for the hole blocking layer is not particularlylimited as long as the material has an energy barrier for preventing theleak of a hole from the emission layer toward a cathode and haselectron-transporting property.

In the present invention, the uppermost layer of the organic compoundlayer 22 to be formed in the step of forming the organic compound layeris preferably a layer formed of a material having a lower solubility inthe polar solvent than the release layer (especially the lowermost layerof the release layer) does. Here, the uppermost layer of the organiccompound layer 22 is an emission layer, a hole blocking layer, anelectron blocking layer, a charge transport layer (a hole transportlayer or an electron transport layer), or a charge injection layer (anelectron injection layer or a hole injection layer). In addition, thematerial having a low solubility in a polar solvent is specifically acondensed polycyclic hydrocarbon compound except a compound having anm-terphenyl group.

Here, the condensed polycyclic hydrocarbon compound is a cyclic,unsaturated organic compound constituted only of a hydrocarbon. Morespecifically, the compound is a compound containing a condensed ringobtained by the condensation of at least one side of an aromatic ringsuch as a benzene ring. Specific examples of the condensed polycyclichydrocarbon compound include naphthalene, fluorene, fluoranthene,chrysene, anthracene, tetracene, phenanthrene, pyrene, and triphenylene.

However, it is hard to utilize the condensed polycyclic hydrocarboncompound as a constituent material for the organic compound layerbecause the compound has low heat stability when used as it is.Therefore, a compound obtained by adding a substituent to such condensedpolycyclic hydrocarbon compound is used as a constituent material forthe organic compound layer.

Here, a compound as a constituent material for, in particular, theuppermost layer of the organic compound layer is preferably an organiccompound obtained by the bonding of the multiple condensed polycyclichydrocarbon compounds except a compound having an m-terphenyl group witha single bond. The organic compound includes a compound obtained byappropriately substituting the condensed polycyclic hydrocarbon compoundas a main skeleton with an alkyl group such as a methyl group or anethyl group. It should be noted that such organic compound does notinclude any compound having a heteroatom (such as N or O) in its mainchain or a substituent thereof.

A layer formed of the condensed polycyclic hydrocarbon compounds hascharge-transporting property.

It should be noted that an existing method such as a vacuum depositionmethod, a spin coating method, a dip coating method, or an ink jetmethod can be employed as a method of forming the layer formed of thearomatic hydrocarbon compound. The film forming-method is morepreferably the vacuum deposition method in consideration of the emissioncharacteristic of the organic EL display device.

(Step of Forming Release Layer)

A release layer 30 to be provided on the organic compound layer 22 maybe a single layer, or may be a laminate formed of multiple layers. Inthe present invention, when the release layer 30 is formed of a singlelayer, the layer is a deposited film formed of a material soluble in apolar solvent. Alternatively, when the release layer 30 is a laminateformed of multiple layers, at least the lowermost layer out of thelayers constituting the laminate is a layer formed of a low-molecularweight material formed into a film by the vacuum deposition method. Morespecifically, the lowermost layer of the release layer 30 is a depositedfilm formed of the material soluble in the polar solvent. When theuppermost layer of the organic compound layer is formed of a materialhaving a low solubility in the polar solvent, the lowermost layer of therelease layer on the layer is formed of a deposited film formed of amaterial soluble in the polar solvent, and the polar solvent is usedupon removal of the release layer, the release layer 30 can beselectively removed. The term “polar solvent” as used herein refers to aliquid formed of one kind of polar solvent or a mixed liquid of multiplekinds of polar solvents, and does not comprehend a mixed liquid of apolar solvent and a non-polar solvent (such as toluene or benzene). Thisis because when a liquid for removing the release layer contains anon-polar solvent, there is a high possibility that the liquid dissolvesthe organic compound layer. In addition, the release layer 30 in thepresent invention is preferably an amorphous film.

Here, the reason why the release layer 30 (or at least the lowermostlayer thereof) is a deposited film formed by the vacuum depositionmethod is described. The deposited film formed by the vacuum depositionmethod is a film that has solidified after passing a gas state at leastonce. Here, the damage received by the organic compound layer 22 uponcontact of a material in the gas state with the surface of the organiccompound layer 22 is relatively small. Accordingly, it can be said thatthe film formation by the vacuum deposition method is a film-formingmethod that does small damage to the organic compound layer 22. Inaddition, a material to be formed into a film by the vacuum depositionmethod is naturally limited to a low-molecular weight compound capableof vaporization in a vacuum state because the vacuum deposition methodis a thin film-forming method applied to a compound having highsublimation property. In addition, the molecular weight of the compoundin the deposited film is small as compared with that of a polymermaterial, and hence an interaction (intermolecular force) betweenmolecules constituting the deposited film is weak and their adsorptionforces to the organic compound layer 22 are also weak. Further, thestates of the molecules in the deposited film formed in an amorphousstate such as the orientations of the molecules with respect to eachother are random. As a result, an intermolecular distance becomes largeas compared with those in a solid state and a crystalline state, andhence a state where the molecules are spread out and a solvent moleculeis easy to enter, that is, a state where the molecules are easilydissolved is established. Accordingly, when the deposited film (of theorganic compound) formed by the vacuum deposition method is used as therelease layer 30, the release layer 30 can be easily removed by beingbrought into contact with the polar solvent.

Specific examples of the polar solvent include water, an organiccompound having a heteroatom (such as N, O, or S), and a mixed solventobtained by mixing water and an organic compound having a heteroatom(such as N, O, or S).

Here, a molecule in a solvent or mixed solvent listed as the polarsolvent necessarily contains a heteroatom, and the heteroatom functionsas a polar site of the molecule in the polar solvent. Then, the polarsite interacts with a polar site in a constituent material for therelease layer, and hence the constituent material for the release layeris dissolved in the polar solvent. In addition, the interaction betweenthe polar sites affects the solubilities of various compounds in thepolar solvent. In consideration of the foregoing, the solubility of thelowermost layer of the release layer in the polar solvent can beimproved as compared with the solubility of the uppermost layer of theorganic compound layer therein by appropriately selecting the polarsolvent while taking into consideration the structure of the compound tobe used as the constituent material for the release layer 30.

A compound that dissolves in the polar solvent is, for example, acompound having a polar site (heteroatom) or a compound having anm-terphenyl group. The compound is more specifically a heterocycliccompound, or an organic compound having an electron-donating orelectron-withdrawing substituent.

(1) Heterocyclic Compound

In the present invention, a heterocyclic compound may be used as theconstituent material for the release layer 30. The term “heterocycliccompound” as used herein refers to, for example, a group of compoundseach containing, as a basic skeleton, a heterocyclic compound such aspyridine, bipyridine, triazine, phenanthroline, quinoline, imidazole,oxazole, thiazole, oxadiazole, and thiadiazole. It should be noted thatwhen such compound contains quinoline as a basic skeleton, the compoundmay be a quinolinate complex. Compounds included in the compound groupof heterocyclic compounds are, for example, the following compounds.

(2) Group of Compounds Each Having m-Terphenyl Group

In the present invention, a compound having an m-terphenyl group may beused as the constituent material for the release layer 30. In addition,the release layer 30 is preferably formed by co-depositing the compoundhaving an m-terphenyl group and the heterocyclic compound from the vaporfrom the viewpoint of its heat stability such as a glass transitiontemperature. Examples of the compound having an m-terphenyl groupinclude the following compounds.

(3) Group of Compounds Each Having Electron-Withdrawing Group

In the present invention, a compound having an electron-withdrawinggroup may be used as the constituent material for the release layer 30.Examples of the compound having an electron-withdrawing group includethe following compounds.

(4) Group of Compounds Each Having Organic Acid Site or Organic AcidDerivative Site

In the present invention, a compound having, as a substituent, anorganic acid or a derivative of the organic acid such as an ester may beused as the constituent material for the release layer 30. Examples ofthe compound having an organic acid site or an organic acid derivativesite include the following compounds.

Of the four kinds of compound groups, one kind may be used alone, or twoor more kinds thereof may be appropriately used in combination from theviewpoint of an improvement in solubility in the polar solvent.

In a heterocyclic compound, charge is localized on a heteroelementexcept carbon (such as N, O, or S). In the case of, for example,pyridine having a nitrogen atom in its ring, the polarity of an entiremolecule is caused by the localization of negative charge on thenitrogen atom. Here, when a polar solvent containing a hydrogen atom ofa hydroxyl group (—OH) or the like on which positive charge is localizedinterposes, a hydrogen bond is formed between the site (N atom) whichthe heterocyclic compound has and on which negative charge is localized,and the hydrogen atom in a polar solvent molecule on which positivecharge is localized. When the hydrogen bond is formed as describedabove, the heterocyclic compound dissolves, or becomes easily soluble,in the polar solvent.

Similarly, a compound whose polarity is caused by the fact that thecompound contains at least a heteroatom (such as N, O, or S) hasimproved solubility in the polar solvent as compared with that of acondensed polycyclic hydrocarbon compound.

For example, the bias of n-electrons occurs in a compound obtained byintroducing an electron-withdrawing group or an electron-donating groupinto an aromatic ring, thereby causing polarization. Here, when anelectron-withdrawing substituent is introduced, negative charge islocalized on the substituent to cause polarity. When anelectron-donating substituent is introduced, positive charge islocalized on the substituent to cause polarity. The occurrence of thepolarity enables an interaction with a solvent molecule of the polarsolvent, thereby improving the solubility in the polar solvent. Thesolubility in the polar solvent can also be improved when the molecularstructure contains an organic acid or an organic acid derivative (suchas an ester).

A substituent whose polarity is caused by the fact that the substituentcontains a heteroatom as described above is, for example, a hydroxylgroup, a thiol group, an enol, a carbonic acid ester, a sulfuric acidester, a boronic acid ester, or a phosphoric acid ester. When a compoundhas any such substituent, an acid-base reaction, a hydrogen bond, aninteraction between polar sites, hydration, or the like in accordancewith the acidity of a proton portion occurs, and hence the compounddissolves in the polar solvent. When an aromatic ring is substitutedwith such functional group as described above, the functional groupserves as an electron-withdrawing group as well.

On the other hand, the size of a molecule itself of an aromatichydrocarbon compound free of any condensed ring, specifically, such acompound that benzene rings are linked to each other with a single bondis small as compared with that of a condensed polycyclic hydrocarboncompound. As a result, the former compound has improved solubility inthe polar solvent as compared with that of the condensed polycyclichydrocarbon compound. Molecules each having an m-terphenyl structure areof structures particularly hard to crystallize because the molecules areof such structures as to hardly orient with respect to each other. As aresult, the solubility in the polar solvent is additionally improved.

In contrast, the condensed polycyclic hydrocarbon compound has extremelypoor solubility in the polar solvent because of the following reasons.The compound shows extremely small bias of n-electrons on its rings, hasno site capable of interacting with a solvent molecule of the polarsolvent, and is large as one unit (basic skeleton). Therefore, the useof such material in the uppermost layer of the organic compound layerenables the protection of any other organic compound layer from thepolar solvent for removing the release layer.

Here, a difference between the solubilities of the constituent materialfor the organic compound layer and the constituent material for therelease layer in the polar solvent is described. Description is given bytaking, as specific examples, the etching rates of: the followingcompound 1 as a compound having a condensed polycyclic hydrocarbon to beused as the constituent material for the organic compound layer; and thefollowing compound A2 to be used as the constituent material for therelease layer.

In the present invention, a larger etching rate means a higherdissolution rate. In addition, a larger etching rate means a highersolubility of a layer having a material of interest in the solvent(polar solvent).

FIG. 3 is a graph illustrating thickness changes in the compound 1 andthe compound A2 over an etching time. Here, FIG. 3 illustrates theresults of the etching of the respective layers when a mixed solventobtained by mixing isopropyl alcohol (IPA) and water so that IPA mayaccount for 60 wt % (hereinafter, sometimes referred to as “IPA/watermixed solvent”) is used as a polar solvent.

As can be seen from FIG. 3, a layer (layer A) formed of the compound 1as a condensed polycyclic hydrocarbon compound shows nearly no thicknessreduction even when the etching time is lengthened. On the other hand,the thickness of a layer (layer B) formed of the compound A2 as aheterocyclic compound reduces over time. When the etching rates of therespective layers are calculated with their etching conditions madeidentical to each other, the etching rate of the layer A is 0.008 nm/secbut the etching rate of the layer B is 0.87 nm/sec, that is, a ratio ofthe latter to the former is about 100.

Here, a ratio (n) between the etching rates of the uppermost layer(layer A) of the organic compound layer and the lowermost layer (layerB) of the release layer by the polar solvent used upon removal of therelease layer under the same temperature conditions can be representedlike the following equation.

$n = \frac{\left\lbrack {{Etching}\mspace{14mu} {rate}\mspace{14mu} {of}\mspace{14mu} {lowermost}\mspace{14mu} {layer}\mspace{14mu} {of}\mspace{14mu} {release}\mspace{14mu} {layer}} \right\rbrack}{\left\lbrack {{Etching}\mspace{14mu} {rate}\mspace{14mu} {of}\mspace{14mu} {uppermost}\mspace{14mu} {layer}\mspace{14mu} {of}\mspace{14mu} {organic}\mspace{14mu} {compound}\mspace{14mu} {layer}} \right\rbrack}$

In the present invention, n needs to be at least larger than 1. n ispreferably larger than 10 (n>10). Here, when the compound 1 is used inthe uppermost layer of the organic compound layer and the compound A2 isused in the lowermost layer of the release layer, n becomes about 100.Accordingly, when the constituent material for the uppermost layer ofthe organic compound layer and the constituent material for thelowermost layer of the release layer are selected in consideration ofthe solubility of each material in the polar solvent, an etching rateratio (ratio of the solubilities) between both layers can be increased.As a result, selective removal of the release layer with the polarsolvent is enabled.

The solubility of a compound as a constituent material for each layer inthe IPA/water mixed solvent varies depending on the weight ratio of IPAin the mixed solvent. FIG. 4 is a graph illustrating the solubilities ofthe compound 1 (condensed polycyclic hydrocarbon compound) and thecompound A2 (heterocyclic compound) in the IPA/water mixed solvent(polar solvent). Here, in the graph of FIG. 4, the axis of abscissaindicates the weight percent concentration of IPA in the IPA/water mixedsolvent, and the axis of ordinate indicates the amount of the condensedpolycyclic hydrocarbon compound or heterocyclic compound to dissolve in1 g of the solvent. As can be seen from FIG. 4, while the amount inwhich the compound 1 (condensed polycyclic hydrocarbon compound)dissolves in 1 g of the IPA/water mixed solvent having an IPAconcentration of 80 wt % is 5 μg, the dissolution amount of the compoundA2 (heterocyclic compound) is 73 μg.

FIG. 4 is also a graph that proves the following items (a) and (b):

(a) when the concentration of IPA in the IPA/water mixed solvent isexcessively high, both the constituent material for the release layerand the constituent material for the organic compound layer dissolve inthe IPA/water mixed solvent at so high rates that a situation in whichthe etching rate ratio (n) is close to 1 is established; and(b) in the case of the item (a), adding water to reduce theconcentration of IPA can enlarge the etching rate ratio (n) whilereducing the dissolution rates of the respective materials.

As described above, the constituent material for the release layer 30 isselected in consideration of factors that dominate the solubility in thepolar solvent such as an interaction between polar sites, a hydrogenbond, and a molecular size. Such selection can increase the solubilityof the release layer 30 in the polar solvent as compared with thesolubility of any layer constituting the adjacent organic compound layertherein, provided that a polar solvent except water involves thefollowing possibility. The difference in solubility does not become solarge depending on the kind and concentration of the solvent, and hencethe etching rate ratio approaches 1.

In such case, the solvent is preferably used as a polar solvent mixedwith water. Specifically, the water content is preferably regulated inan appropriate fashion so that the etching rate of the release layer maybe even larger than that of the organic compound layer. The watercontent is more preferably regulated in an appropriate fashion so thatthe etching rate ratio (n) of the release layer to the layer positionedat the uppermost layer in the organic compound layer may exceed 10. As aresult, a more selective removal of the release layer is enabled andhence reductions in the characteristics of the organic EL display devicecan be prevented.

(Step of Processing Release Layer)

In the present invention, a photolithography method can be suitablyutilized as means for patterning (processing) the release layer 30 intoa desired shape. Here, a processing process for the release layerinvolving utilizing the photolithography method is described.

(i) Steps of Forming and Processing Photosensitive Resin Layer

When the photolithography method is utilized, a photosensitive resinlayer 40 needs to be provided on the release layer 30 first. A knownmaterial can be used as a photosensitive resin as a constituent materialfor the photosensitive resin layer 40. In addition, an existing methodsuch as a spin coating method, a dip coating method, or an ink jetmethod can be employed as a method of forming the photosensitive resinlayer 40. A vacuum deposition method can be utilized in some situations.

After the formation of the photosensitive resin layer 40, thephotosensitive resin layer 40 is processed. Here, the step of processingthe photosensitive resin layer 40 is divided into the exposure of thephotosensitive resin layer (exposing step) and the development of thephotosensitive resin layer (developing step).

Here, an existing photoirradiation apparatus can be used in the exposingstep. It should be noted that an exposure apparatus in accordance withthe fineness of a pattern has only to be used. In addition, uponperformance of the exposing step, a photomask 50 having an opening isused in a region to be exposed. It should be noted that a generalphotomask having, on a light transmissive base substrate, alight-shielding region formed of a Cr thin film in accordance with apattern to be formed can be used as the photomask. Meanwhile,ultraviolet light or visible light can be utilized as light with whichthe photosensitive resin layer 40 is irradiated in the exposing step.

By the way, upon performance of the exposing step, the exposure regionof the photosensitive resin layer 40 is desirably determined inconsideration of the nature of the photosensitive resin as theconstituent material for the photosensitive resin layer 40.Specifically, when a positive photosensitive resin is used, a regionfrom which one wishes to remove the photosensitive resin layer 40 in thenext developing step is defined as the exposure region. On the otherhand, when a negative photosensitive resin is used, a region where he orshe wishes to leave the photosensitive resin layer 40 when the nextdeveloping step is performed is defined as the exposure region. Here,FIG. 2E illustrates the case where a positive photosensitive resin isused. In FIG. 2E, a region 42 out of the photosensitive resin layer 40irradiated with ultraviolet light 51 is removed in the next developingstep. Meanwhile, a region 41 shielded from the ultraviolet light withthe photomask 50 serves to protect the organic compound layer 22 aprovided for a predetermined region (the first sub-pixel 20) in the stepof processing the release layer or the step of processing the organiccompound layer to be performed later.

Upon performance of the developing step, a developer suitable for thephotosensitive resin as the constituent material for the photosensitiveresin layer 40 has only to be used.

(ii) Step of Processing Release Layer

Next, the release layer 30 is processed by selectively removing a regionout of the release layer 30 not covered with the photosensitive resinlayer 40. Although a method of selectively removing the release layer 30is not particularly limited, specifically, an existing thinfilm-processing method such as wet etching or dry etching can beemployed, provided that the dry etching in which an influence of sideetching by a solvent is smaller than that of any other method ispreferred because a reduction in pattern accuracy can be suppressed.

In the foregoing description, a photolithography process involving usinga photoresist is utilized as means for processing the release layer 30,but a method of processing the release layer 30 is not limited thereto.For example, the release layer may be patterned into a desired shape byutilizing an ink jet mode, printing, laser processing, or the like. Inthis case, the release layer patterned into the desired shape can beformed without the formation of any photoresist. Accordingly, it isrecommended that the release layer 30 be utilized as an etching maskupon processing of the organic compound layer in the next step (step ofprocessing the organic compound layer). It should be noted that uponutilization of the release layer 30 as an etching mask, the thickness ofthe release layer 30 is preferably at least larger than that of theorganic compound layer.

(Step of Processing Organic Compound Layer)

Next, the organic compound layer 22 in a region out of the organiccompound layer 22 not covered with the release layer 30 is selectivelyremoved. A method of processing the organic compound layer 22 is notparticularly limited, and an existing method such as wet etching or dryetching can be employed, provided that the dry etching is preferredbecause no concern is raised about side etching by a solvent.

Through the foregoing process, the organic compound layer can be formedso as to be selectively provided only for a predetermined sub-pixel. Inaddition, the organic compound layer desired only for each sub-pixel canbe selectively formed in the sub-pixel by repeatedly performing thesteps ranging from the step of forming the organic compound layer to thestep of processing the organic compound layer described above a numberof times corresponding to the number of kinds of sub-pixels.

(Step of Removing Photosensitive Resin Layer)

In the manufacturing method of the present invention, after theprocessing of the organic compound layer 22 has been performed, therelease layer 30 and the photosensitive resin layer 41 laminated on theorganic compound layer 22 are each removed.

When the photosensitive resin layer 40 is removed, an existing methodsuch as wet etching or dry etching can be employed. In the presentinvention, the dry etching that raises no concern about side etching bya solvent is preferred because a reduction in pattern accuracy can besuppressed.

(Step of Removing Release Layer)

The release layer 30 is removed with the polar solvent. The releaselayer 30 is particularly preferably removed after the patterning of theorganic compound layers 22 a, 22 b, and 22 c has been completed andafter a layer above the release layer has been removed. This is becausereductions in element characteristics due to the inclusion of animpurity in, for example, a layer such as a photoresist to be formedabove the release layer, or a developer or release liquid for thephotoresist into the organic compound layer during the process can beavoided. In addition, the solvent is more preferably a solventcontaining water. It should be noted that one kind of polar solvent maybe incorporated into the solvent, or a mixture of multiple kinds ofpolar solvents may be incorporated into the solvent.

Here, the term “polar solvent” refers to an organic solvent havingpolarity. Examples thereof include alcohols, polyhydric alcohols,ketones, esters, pyridines, and ethers, provided that a solvent having aboiling point at least lower than the decomposition temperature or glasstransition temperature of the organic compound in the organic compoundlayer 22 is preferably selected because the solvent needs to be removedby being volatilized in the step to be described later. In the cases of,for example, the alcohols, methanol, ethanol, isopropyl alcohol, or thelike can be suitably used.

The removal of the release layer 30 exposes the uppermost layer of theorganic compound layer 22. At this time, the etching rate of theuppermost layer of the organic compound layer 22 is slow as comparedwith that of the release layer 30 because the constituent material forthe uppermost layer of the organic compound layer 22 is a condensedpolycyclic hydrocarbon compound. As a result, in the step of removingthe release layer, the uppermost layer of the organic compound layer 22is substantially free of being dissolved, and hence the release layer 30can be selectively removed while an end portion of the organic compoundlayer 22 is substantially prevented from damaging. In addition, in thestep, the uppermost layer of the organic compound layer is substantiallyfree of being dissolved, and hence the organic compound layer remainsnearly intact. Accordingly, its thickness can be managed in anadditionally strict fashion. The thickness is of particular importanceupon control of a luminescent color by means of a cavity effect.Accordingly, the ability to manage the thickness in an additionallystrict fashion leads to the reduction of a characteristic variation in adisplay device or between display devices, thereby enabling an increasein yield.

After the removal of the release layer 30, the solvent remaining on thesupporting substrate 10 provided with the organic compound layer 22 oron the organic compound layer 22 is preferably removed by heating thesupporting substrate 10. The supporting substrate 10 is more preferablyheated under a vacuum condition at about 80° C. When the solvent isremoved by heating the supporting substrate 10 as described above, acharge injection layer or a charge transport layer can be formed in thenext step in a state where the formation is not affected by the solvent.It should be noted that the supporting substrate 10 may be heated in avacuum before the performance of the next step. The vacuum heating canalso reduce an influence such as the adhesion of water, oxygen, orforeign matter in the atmosphere.

(Step of Forming Charge Injection/Transport Layer)

After the removal of the release layer 30, the chargeinjection/transport layer 23 is formed on the organic compound layer 22.It should be noted that the charge injection/transport layer 23 ispreferably formed as a layer common to the respective sub-pixels. Inaddition, the manufacturing method of the present invention is a methodsuitable upon formation of a layer containing an alkali metal componentor an alkaline-earth metal component as a charge injection layer.

When an electron injection layer is formed as the chargeinjection/transport layer 23, an electron injection material as aconstituent material for the electron injection layer desirably has ahigh work function. Examples of such material include an alkali metal,an alkaline-earth metal, a material obtained by doping an electrontransport material with an alkali metal, an alkali metal compound(oxide, carbonate, or halogenated salt), and an alkaline-earth metalcompound (oxide, carbonate, or halogenated salt). Here, cesium,potassium, and lithium can be given as specific examples of the alkalimetal. In addition, specific examples of the alkaline-earth metalinclude calcium and barium.

On the other hand, when a hole injection layer is formed as the chargeinjection/transport layer 23, an organic compound having a small workfunction and an electron-withdrawing material having an extremely deepwork function can be suitably given as examples of a hole injectionmaterial as a constituent material for the hole injection layer. Anarylamine compound and phthalocyanine can be given as examples of theorganic compound having a small work function. In addition, F4-TCNQ, anazatriphenylene compound (such as PPDN orhexacyano-hexaazatriphenylene), molybdenum oxide, and tungsten oxide canbe given as examples of the electron-withdrawing material having a deepwork function.

(Step of Forming Second Electrode)

When a top emission type organic EL display device is produced, thesecond electrode 24 corresponding to the upper electrode is atransparent electrode formed of a transparent conductive material. Thetransparent conductive material having light-transmitting property ispreferably a material having a high light transmittance. Examples ofsuch material include: transparent conductive materials such as ITO,indium zinc oxide, and ZnO; and organic conductive materials such as apolyacetylene. It should be noted that a semitransmissive film obtainedby forming a metal material such as Ag or Al into a film having athickness of about 10 nm to 30 nm may be used as the second electrode24. Here, when a light transmissive electrode is formed of a transparentconductive material such as ITO, indium zinc oxide, or ZnO, compositionthat satisfies both a low resistance characteristic required for thecomposition to be used in an electrode and a high transmittancecharacteristic needed for an improvement in light extraction efficiencyis preferred for a reduction in power consumption. A thin film to serveas the light transmissive electrode can be formed by a known method suchas sputtering. When a transparent conductive film that brings togetherthe low resistance characteristic and the high transmittancecharacteristic is produced, the volume of a film-forming apparatus, atarget, the pressure in the apparatus, and an output voltage at the timeof the film formation need to be appropriately adjusted. It should benoted that the second electrode 24 is electrically connected to aswitching element such as a transistor (not shown). As described above,the manufacturing method of the present invention is a manufacturingmethod without using a fine metal mask. Therefore, the manufacture of anorganic EL display device having as fine a pixel size as about 10 μm anda large supporting substrate size in its fifth generation and afterwardcan be realized.

(Driving Method of Organic EL Display Device)

The organic EL display device manufactured by the manufacturing methodof the present invention can be driven by applying a voltage between thefirst electrode 21 and the second electrode 24 which each sub-pixel (20a, 20 b, or 20 c) has. Here, when the voltage is applied, for example,power source means (not shown) electrically connected to each electrodethrough a transistor is used.

Embodiment 2

FIGS. 5A to 5E are each a schematic sectional view illustratingEmbodiment 2 in the method of manufacturing an organic EL display deviceof the present invention. Here, Embodiment 2 differs from Embodiment 1in that a protective layer 60 is formed on the release layer 30 afterthe step of forming the release layer 30 (FIG. 5A). Hereinafter,Embodiment 2 is described with particular emphasis on its differencefrom Embodiment 1.

(Step of Forming Protective Layer)

In the manufacturing method of the present invention, as illustrated inFIG. 5A, the protective layer 60 may be formed on the release layer 30after the step of forming the release layer 30. Here, the protectivelayer 60 to be formed on the release layer 30 is a film insoluble inwater and an organic solvent, and is preferably a film having moistureresistance and gas barrier property. Here, the protective layer 60 morepreferably has such characteristic as to absorb light to be applied atthe time of photolithography. The protective layer 60 to be formed inthe manufacturing method of the present invention is preferably athin-film layer of an inorganic compound using silicon nitride (SiN) asa main material.

By the way, the formation of the protective layer 60 on the releaselayer 30 eliminates the possibility that the solvent to be used uponformation of the photosensitive resin layer 40 in the next steppermeates the release layer 30 to contact the organic compound layer 22.Accordingly, upon selection of the solvent of the photosensitive resinlayer 40, such a restraint that the solvent should not dissolve theorganic compound layer 22 is lifted, and hence an additionally cheapmaterial can also be selected.

(Step of Processing Protective Layer)

When the protective layer 60 is provided between the photosensitiveresin layer 40 and the release layer 30, the processing of theprotective layer 60 needs to be performed before the processing of therelease layer 30 is performed. Here, the processing of the protectivelayer 60 is specifically selective removal of a region out of theprotective layer 60 not covered with a photosensitive resin layer 41(photosensitive resin not exposed in the exposing step) (FIG. 5B).Although a method of selectively removing the protective layer 60 is notparticularly limited, a known technology such as wet etching or dryetching can be utilized. For example, when a constituent material forthe protective layer 60 is SiN, dry etching involving using CF₄ as areactant gas can be utilized.

(Step of Removing Protective Layer Etc.)

After the step of processing the protective layer described above hasbeen performed, the processing of the release layer 30 and the organiccompound layer 22 a is performed in the same manner as in Embodiment 1(FIG. 5C). It should be noted that the photosensitive resin layer 41 maybe removed simultaneously upon performance of the processing of theorganic compound layer 22 a.

After that, the steps ranging from the formation of the organic compoundlayer (22 b or 22 c) to the processing of the organic compound layer areperformed in each sub-pixel (FIG. 5D), and then the protective layer 60and the release layer 30 are removed (FIG. 5E). When the protectivelayer 60 is provided between the release layer and the photosensitiveresin layer 40 like this embodiment, the protective layer 60 is removedby a method (such as dry etching or wet etching) utilized during thestep of processing the protective layer after the removal of thephotosensitive resin layer 40. After that, the release layer 30 isremoved with the polar solvent. Alternatively, the protective layer 60may be removed together with the release layer 30 by selectivelyremoving the release layer 30 with the polar solvent in a state wherethe protective layer 60 is not removed.

Embodiment 3

FIGS. 6A to 6F are each a schematic sectional view illustratingEmbodiment 3 in the method of manufacturing an organic EL display deviceof the present invention. Here, Embodiment 3 differs from Embodiment 2in that a protective layer 60 is formed of multiple layers (a firstprotective layer 61 and a second protective layer 62) (FIG. 6A).Hereinafter, Embodiment 3 is described with particular emphasis on itsdifference from Embodiment 2.

(Step of Forming Protective Layer)

As illustrated in FIG. 5A and FIG. 6A, the protective layer 60 may be asingle layer, or may be multiple layers. When the protective layer is alaminate formed of two layers, a first protective layer 61 to be formedfirst is preferably formed of a water-soluble material. In addition, asecond protective layer 62 to be formed subsequently to the firstprotective layer 61 is preferably a film of an inorganic compound using,as a main material, a material insoluble in water and an organic solventsuch as silicon nitride.

Examples of the water-soluble material as a constituent material for thefirst protective layer 61 include known water-soluble polymer materialssuch as a polyvinyl alcohol, a polyethylene glycol, and a polyvinylpyrrolidone. In addition, an existing method such as a known spincoating method, dip coating method, or ink jet method can be employedupon formation of the first protective layer. Here, the organic compoundlayer 22 is not etched by a solvent upon formation of the firstprotective layer 61 because the organic compound layer 22 is a layerformed of a material that does not dissolve in water. In addition, whenthe protective layer 60 is formed so as to have a large thickness, aninfluence such as the dissolution of the organic compound layer 22 bythe solvent of the photosensitive resin layer 40, a reduction in thethickness of the organic compound layer 22, or the elution of aluminescence material can be additionally alleviated.

(Step of Processing Protective Layer)

In addition, when the protective layer 60 is constituted of multiplelayers, each protective layer needs to be processed. For example, whenthe protective layer 60 is a laminate obtained by laminating the firstprotective layer 61 formed of a water-soluble polymer and the secondprotective layer 62 formed of SiN in the stated order from the substrate10 side, each protective layer is processed by the following method.First, the second protective layer as an upper layer is subjected to dryetching involving using CF₄ as a reactant gas (FIG. 6B), and then thefirst protective layer as a lower layer is subjected to dry etchinginvolving using CF₄ as a reactant gas (FIG. 6C).

(Step of Removing Protective Layer Etc.)

After the step of processing the protective layer described above hasbeen performed, the processing of the release layer 30 and the organiccompound layer 22 a is performed in the same manner as in Embodiment 2(FIG. 6D). It should be noted that, as illustrated in FIG. 6D, theremoval of the photosensitive resin layer 41 may be simultaneouslyperformed upon performance of the processing of the organic compoundlayer 22 a.

After that, the steps ranging from the formation of the organic compoundlayer (22 b or 22 c) to the processing of the organic compound layer areperformed in each sub-pixel (FIG. 6E), and then the protective layer 60and the release layer are removed (FIG. 6F). When the protective layer60 is provided between the release layer and the photosensitive resinlayer 40 like this embodiment, the protective layer 60 is removed by amethod (such as dry etching or wet etching) utilized during the step ofprocessing the protective layer after the removal of the photosensitiveresin layer 40. After that, the release layer 30 is removed with thepolar solvent. Alternatively, the following may be adopted. While thephotosensitive resin layer 40 is not removed, the first protective layer61 is selectively dissolved by being brought into contact with water sothat the second protective layer 62 and the photosensitive resin layer40 formed on the first protective layer 61 may be removed together.After that, the release layer 30 is removed with the polar solvent.Alternatively, the following may be adopted. While the photosensitiveresin layer 40 and the protective layer 60 are not removed, the releaselayer 30 is removed with the polar solvent so that the layers may beremoved together with the release layer.

Next, the present invention is described by way of examples. However,the present invention is not limited to the examples to be describedbelow. For example, the order in which sub-pixels are formed in terms oftheir luminescent colors is not limited to the order “blue, green, andred.” For example, the constitution and thickness of the organiccompound layer are also not limited to the information described in theexamples. For example, when an electron is injected from the firstelectrode, the order in which the layers of the organic compound layerare laminated in accordance with the injection has only to be adopted. Acombination of the examples to be described below is also included inthe present invention. A well-known or known technology in the technicalfield is applied to a portion not specifically illustrated or describedin the specification.

Example 1

The organic EL display device illustrated in FIG. 1 was produced inaccordance with the process illustrated in FIGS. 2A to 2O.

(1) Step of Forming First Electrode

First, by a sputtering method, an aluminum alloy (AlNd) was formed intoa film on a supporting substrate 10 so that an AlNd film (reflectingelectrode) was formed. At this time, the thickness of the AlNd film wasset to 100 nm. Then, by a sputtering method, ITO was formed into a filmon the AlNd film so that an ITO film was formed. At this time, thethickness of the ITO film was set to 10 nm. It should be noted that alaminate formed of the AlNd film and the ITO film functioned as thefirst electrode 21. Next, the first electrodes 21 a, 21 b, and 21 cconstituting the first sub-pixel, the second sub-pixel, and the thirdsub-pixel, respectively were each produced by performing the patterningof the first electrode 21 based on a photolithography process (FIG. 2A).

(2) Step of Forming Blue Organic Compound Layer

The blue organic compound layer 22 a was formed on the supportingsubstrate 10 on which the patterned first electrodes (21 a, 21 b, and 21c) had been formed by continuous film formation involving employing avacuum deposition method. First, a hole transport layer was formed so asto have a thickness of 120 nm, and then an emission layer containing ablue luminescence material was formed so as to have a thickness of 30nm. Next, a condensed polycyclic hydrocarbon compound represented by thefollowing formula [1] was formed into a film so that a hole blockinglayer was formed. At this time, the thickness of the hole blocking layerwas set to 10 nm. Thus, the organic compound layer 22 a (blue organiccompound layer) was formed (FIG. 2B).

(3) Step of Forming Release Layer

Next, a phenanthroline derivative represented by the following formula[2] was formed into a film by a vacuum deposition method so that therelease layer 30 was formed. At this time, the thickness of the releaselayer 30 was set to 500 nm (FIG. 2C).

(4) Steps of Forming and Processing Photosensitive Resin Layer

Next, a positive photoresist (available under the product name “AZ1500”from AZ Electronic Materials) was formed into a film by a spin coatingmethod so that the photosensitive resin layer 40 was formed (FIG. 2D).At this time, the thickness of the photosensitive resin layer was 1,000nm. Next, exposure to the ultraviolet light 51 was performed with anexposure apparatus (Mask Aligner MPA600 manufactured by Canon Inc.) in astate where the photosensitive resin layer 41 provided for the region ofthe first sub-pixel 20 a was shielded with the photomask 50 so that thephotosensitive resin layer 41 was left (FIG. 2E). At this time, anexposure time was 40 s. After the exposure, development was performedwith a developer (prepared by diluting a product available under theproduct name “312MIF” from AZ Electronic Materials with water so thatits concentration was 50%) for 1 minute. A photosensitive resin layer 42exposed to the ultraviolet light 51 was removed by the developingtreatment.

(5) Steps of Processing Release Layer and Blue Organic Compound Layer

Next, the release layer 30 not covered with the photosensitive resinlayer 41 was removed and patterned with oxygen as a reactant gas underthe conditions of a flow rate of 20 sccm, a pressure of 8 Pa, an outputof 150 W, and a reaction time of 2 minutes. Thus, the patterned releaselayer 30 was formed in the region of the first sub-pixel 20 a (FIG. 2F).Further, the blue organic compound layer 22 a provided for the regionexcept the region of the first sub-pixel 20 a was selectively removed bydry etching under the same conditions. Thus, the organic compound layer22 a (blue organic compound layer) was formed in the region of the firstsub-pixel 20 a (FIG. 2G).

(6) Steps of Forming and Processing Red Organic Compound Layer

Next, the red organic compound layer 22 b was formed by continuous filmformation involving employing a vacuum deposition method. First, a holetransport layer was formed so as to have a thickness of 200 nm, and thenan emission layer containing a red luminescence material was formed soas to have a thickness of 30 nm. Next, the condensed polycyclichydrocarbon compound represented by the formula (1) was formed into afilm so that a hole blocking layer was formed. At this time, thethickness of the hole blocking layer was set to 10 nm. Thus, the organiccompound layer 22 b (red organic compound layer) was formed. Next, thephenanthroline derivative represented by the formula (2) was formed intoa film by a vacuum deposition method so that the release layer 30 wasformed. At this time, the thickness of the release layer 30 was set to500 nm. Next, the positive photoresist used in the step (4) was formedinto a film by a spin coating method so that the photosensitive resinlayer 40 was formed (FIG. 2H). At this time, the thickness of thephotosensitive resin layer was 1,000 nm. Next, the photosensitive resinlayer 40 was processed by the same method as that in the step (4), andthen the release layer 30 and the organic compound layer 22 b wereprocessed by the same methods as those in the step (5). Thus, theorganic compound layer 22 b (red organic compound layer) was formed inthe region of the second sub-pixel 20 b (FIG. 21).

(7) Steps of Forming and Processing Green Organic Compound Layer

Next, the green organic compound layer 22 c was formed by continuousfilm formation involving employing a vacuum deposition method. First, ahole transport layer was formed so as to have a thickness of 160 nm, andthen an emission layer containing a green luminescence material wasformed so as to have a thickness of 30 nm. Next, the condensedpolycyclic hydrocarbon compound represented by the formula (1) wasformed into a film so that a hole blocking layer was formed. At thistime, the thickness of the hole blocking layer was set to 10 nm. Thus,the organic compound layer 22 c (green organic compound layer) wasformed. Next, the phenanthroline derivative represented by the formula(2) was formed into a film by a vacuum deposition method so that therelease layer 30 was formed. At this time, the thickness of the releaselayer 30 was set to 500 nm. Next, the positive photoresist used in thestep (4) was formed into a film by a spin coating method so that thephotosensitive resin layer 40 was formed (FIG. 2J). At this time, thethickness of the photosensitive resin layer was 1,000 nm. Next, thephotosensitive resin layer 40 was processed by the same method as thatin the step (4), and then the release layer 30 and the organic compoundlayer 22 b were processed by the same methods as those in the step (5).Thus, the organic compound layer 22 c (green organic compound layer) wasformed in the region of the third sub-pixel 20 c (FIG. 2K).

(8) Steps of Removing Photosensitive Resin Layer and Release Layer

Next, the photosensitive resin layer 41 was removed by performing dryetching with oxygen as a reactant gas under the conditions of a flowrate of 20 sccm, a pressure of 8 Pa, and an output of 150 W (FIG. 2L).Next, the release layer 30 was removed with a mixed solvent obtained bymixing water and IPA so that an IPA concentration was 60 wt % (FIG. 2M).It should be noted that as the etching rate of the compound(phenanthroline derivative represented by the formula (2)) constitutingthe release layer 30 in this example was 0.9 nm/sec, the release layer30 was removed through immersion in the mixed solvent for 600 seconds.Next, vacuum heating was performed at 80° C. so that the solventremaining on the organic compound layer was removed. It should be notedthat the etching rate of the compound represented by the formula (1)serving as the uppermost layer of the organic compound layer placed ineach sub-pixel for the polar solvent used for removing the release layeris about 0.0045 nm/sec, which is sufficiently small as compared with theetching rate of the release layer 30.

(9) Step of Producing Second Electrode Etc.

Next, the compound represented by the formula (2) (compound A2) wasformed into a film so that a charge transport layer (electron transportlayer) was formed. At this time, the thickness of the charge transportlayer was set to 20 nm. Next, the compound represented by the formula(2) and cesium carbonate (Cs₂CO₃) were co-deposited from the vapor sothat an electron injection layer was formed. At this time, the thicknessof the electron injection layer was set to 20 nm (FIG. 2N).

Next, an Ag film having a thickness of 16 nm was formed by sputtering sothat the semitransparent second electrode was formed (FIG. 20).

Next, a sealing glass (not shown) was bonded to the substrate under anitrogen atmosphere so that a structure for preventing elementdeterioration was established. Thus, the organic EL display device wasproduced.

The organic EL display device 1 thus produced was evaluated by beingcompared with: an organic EL display device produced by employingphotolithography in the same manner as in this example except that a PVPwas used as a release layer; and an organic EL display device similarlyproduced except that the respective organic compound layers like apattern were formed with a metal mask in a vacuum in-situ fashion. Thedevice 1 was superior in current efficiency and drive durability life tothe organic EL display device produced by using the PVP as a releaselayer, and obtained values for the parameters were comparable to thoseof the device in which the organic compound layers were formed in avacuum in-situ fashion. This probably results from the achievement ofthe avoidance of a reduction in efficiency and the deterioration of thelife attributable to the following fact. The deposited film formed bythe vacuum deposition method was used as the release layer, and henceits removal was attained while the amount of the residue was reduced ascompared with that in the case of the PVP. With regard to an increase infineness, the employment of the photolithography method enabled thereduction of a pixel size to 9 μm square while the smallest pixel sizeobtained by a vapor deposition method involving using a fine metal maskwas about 100 μm square.

Example 2

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the following compound A7(etching rate: 1.6 nm/sec) was used as a constituent material for therelease layer 30. In addition, an immersion time in an IPA/water mixedsolvent having the same mixing ratio as that in Example 1 upon removalof the release layer 30 was set to 330 seconds.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 3

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the following compound B1(etching rate: 1.3 nm/sec) was used as a constituent material for therelease layer 30. In addition, an immersion time in an IPA/water mixedsolvent having the same mixing ratio as that in Example 1 upon removalof the release layer 30 was set to 400 seconds.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 4

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the following compound Cl(etching rate: 1.5 nm/sec) was used as a constituent material for therelease layer 30. In addition, an immersion time in an IPA/water mixedsolvent having the same mixing ratio as that in Example 1 upon removalof the release layer 30 was set to 340 seconds.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 5

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the following compound D6(etching rate: 2.5 nm/sec) was used as a constituent material for therelease layer 30. In addition, an immersion time in an IPA/water mixedsolvent having the same mixing ratio as that in Example 1 upon removalof the release layer 30 was set to 220 seconds.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 6

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the following compound D8(etching rate: 3.0 nm/sec) was used as a constituent material for therelease layer 30. In addition, an immersion time in an IPA/water mixedsolvent having the same mixing ratio as that in Example 1 upon removalof the release layer 30 was set to 180 seconds.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 7

An organic EL display device was manufactured in the same manner as inExample 1 except the following. In Example 1, the step of forming theprotective layer 60 was added between the step of forming the releaselayer 30 and the step of forming the photosensitive resin layer 40 to beperformed upon processing of the organic compound layer (22 a, 22 b, or22 c). In addition, the step of processing the protective layer 60 wasadded between the step of processing the photosensitive resin layer 40and the step of processing the release layer 30. Further, the step ofremoving the protective layer 60 was added between the step of removingthe photosensitive resin layer 41 and the step of removing the releaselayer 30. Hereinafter, a manufacturing process in this example isdescribed with reference to FIGS. 5A to 5E with particular emphasis onthe step of forming the protective layer, the step of processing theprotective layer, and the step of removing the protective layer.

(1) Step of Forming Protective Layer Etc.

First, the layers up to the release layer 30 were formed on thesupporting substrate 10 by the same methods as those in Example 1. Next,silicon nitride (SiN) was formed into a film by a CVD method on therelease layer 30 so that the protective layer 60 was formed. At thistime, the thickness of the protective layer 60 was set to 1,000 nm.Next, the photosensitive resin layer 40 was formed on the protectivelayer 60 by the same method as that in Example 1 (FIG. 5A).

(2) Step of Processing Protective Layer

Next, the photosensitive resin layer 40 was patterned. After that, theprotective layer 60 not covered with the photosensitive resin layer 41was removed with CF₄ as a reactant gas under the conditions of a flowrate of 30 sccm, an output of 150 W, a pressure of 10 Pa, and atreatment time of 7 minutes (FIG. 5B). That is, the protective layer 60was processed in the step so that the protective layer 60 was providedin correspondence with the region of each sub-pixel.

(3) Step of Processing Organic Compound Layer

After that, the steps of processing the release layer 30 and the organiccompound layer 22 a were performed by the same methods as those inExample 1 (FIG. 5C). Next, the steps (1) and (2) were performed in eachof the second sub-pixel 20 b and the third sub-pixel 20 c so that theorganic compound layers 22 b and 22 c to be provided for the secondsub-pixel 20 b and the third sub-pixel 20 c, respectively were formedand processed (FIG. 5D).

(4) Step of Removing Protective Layer

Next, the photosensitive resin layer 41 was removed by the same methodas that in Example 1. After that, the protective layer 60 was removedwith CF₄ as a reactant gas under the conditions of a flow rate of 30sccm, an output of 150 W, a pressure of 10 Pa, and a treatment time of 7minutes. Next, the release layer 30 was removed by the same method asthat in Example 1 (FIG. 5E). After that, the charge injection/transportlayer 23 and the second electrode 24 were formed in the stated order bythe same methods as those in Example 1. Thus, the organic EL displaydevice was obtained.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

Example 8

In this example, an organic EL display device was manufactured in thesame manner as in Example 7 except that the step of forming theprotective layer, the step of processing the protective layer 60, andthe step of removing the protective layer 60 in Example 7 were changedto methods to be described below. Hereinafter, description is given withreference to FIGS. 6A to 6F with particular emphasis on the step offorming the protective layer, the step of processing the protectivelayer, and the step of removing the protective layer.

(1) Step of Forming Protective Layer

First, the layers up to the release layer 30 were formed on thesupporting substrate 10 by the same methods as those in Example 7. Next,an aqueous solution of a polyvinyl pyrrolidone (PVP, molecular weight:360,000) as a water-soluble polymer material was prepared by mixing thePVP and water so that the weight concentration of the PVP was 5 wt %.Next, the prepared aqueous solution of the PVP was applied onto therelease layer 30 by a spin coating method, and was then dried so thatthe first protective layer 61 was formed. At this time, the thickness ofthe first protective layer 61 was 500 nm. Next, silicon nitride (SiN)was formed into a film by a CVD method on the first protective layer 61so that the second protective layer 62 was formed. At this time, thethickness of the second protective layer 62 was set to 1,000 nm. Next,the photosensitive resin layer 40 was formed on the protective layer 60by the same method as that in Example 7 (FIG. 6A).

(2) Step of Processing Protective Layer

After the photosensitive resin layer 40 had been patterned so as to beleft in the region of the first sub-pixel, the processing of the secondprotective layer 62 (selective removal of the second protective layer62) was performed under conditions identical to those of the step (2) ofExample 7 (FIG. 6B). Next, the first protective layer 61 not coveredwith the photosensitive resin layer 40 was removed with oxygen as areactant gas under the conditions of a flow rate of 20 sccm, a pressureof 8 Pa, an output of 150 W, and 5 minutes. That is, the protectivelayer 60 formed of the first protective layer 61 and the secondprotective layer 62 was processed in the step so that the protectivelayer 60 was provided in correspondence with the region of eachsub-pixel (FIG. 6C).

(3) Step of Processing Organic Compound Layer

The release layer 30 and the organic compound layer 22 a were processedwith the photosensitive resin layer 40 and the protective layer 60 asmasks in the same manner as in Example 1 (FIG. 6D). The steps (1) and(2) were performed in each of the second sub-pixel 20 b and the thirdsub-pixel 20 c so that the organic compound layers 22 b and 22 c to beprovided for the second sub-pixel 20 b and the third sub-pixel 20 c,respectively were formed and processed (FIG. 6E).

(4) Step of Removing Protective Layer

The second protective layer 62 was removed in the same manner as in thestep (4) of Example 7 after the removal of the photosensitive resinlayer 40. Next, the first protective layer 61 was removed with oxygen asa reactant gas under the conditions of a flow rate of 20 sccm, apressure of 8 Pa, an output of 150 W, and 5 minutes. Next, the releaselayer 30 was removed by the same method as that in Example 7 (FIG. 6F).After that, the charge injection/transport layer 23 and the secondelectrode 24 were formed in the stated order by the same methods asthose in Example 7. Thus, the organic EL display device was obtained.

The resultant organic EL display device was evaluated by the samemethods as those in Example 1. As a result, the device provided resultscomparable to those in Example 1 in terms of its current efficiency,drive life, and fineness.

As described above, the organic EL display device formed by themanufacturing method according to the present invention can find use inthe display portions of various electronic equipments because the deviceis excellent in current efficiency, drive life, and fineness. Examplesof the electronic equipments include digital cameras, portableequipments such as a personal digital assistant, personal computers,televisions, and various printers.

A digital camera as an example of the electronic equipments isdescribed. FIG. 7 illustrates a block diagram of a digital camerasystem. A digital camera system 71 includes a photographing portion 72,an image signal processing circuit 73, a display device 74 according tothe present invention, a memory 75, a CPU 76, and an operation portion77. An image photographed by the photographing portion 72 or imageinformation recorded in the memory 75 is subjected to signal processingin the image signal processing circuit 73 so that an image signal may beproduced. The image signal can be displayed on the display device 74. Acontroller has the CPU 76 for controlling, for example, thephotographing portion 72, the memory 75, and the image signal processingcircuit 73 with an input from the operation portion 77, and performsphotographing, recording, reproduction, and display suitable forsituations.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

This application claims the benefit of Japanese Patent Application Nos.2011-099393, filed Apr. 27, 2011, and 2012-068006, filed Mar. 23, 2012,which are hereby incorporated by reference herein in their entirety.

1. A method of manufacturing an organic electroluminescence displaydevice comprising an organic electroluminescence element including afirst electrode and a second electrode, and an organic compound layerarranged between the first electrode and the second electrode, theorganic compound layer being patterned, the method comprising: anorganic compound layer-forming step of forming the organic compoundlayer at least on the first electrode; a release layer-forming step offorming a release layer on the organic compound layer; a releaselayer-processing step of processing the release layer; an organiccompound layer-processing step of removing the organic compound layer ina region not covered with the release layer processed in the releaselayer-processing step; and a release layer-removing step of removing therelease layer with a polar solvent, wherein: the organic compoundlayer-forming step comprises the step of forming an uppermost layer ofthe organic compound layer from a condensed polycyclic hydrocarboncompound except a compound having an m-terphenyl group; and the releaselayer-forming step comprises the step of forming a compound soluble inthe polar solvent in at least a lowermost layer of the release layer bya vapor deposition method.
 2. The method of manufacturing an organicelectroluminescence display device according to claim 1, wherein thecompound soluble in the polar solvent in the release layer-forming stepcomprises one of a compound having a polar site and a compound having anm-terphenyl group.
 3. The method of manufacturing an organicelectroluminescence display device according to claim 1, wherein thepolar solvent used in the release layer-removing step contains water. 4.The method of manufacturing an organic electroluminescence displaydevice according to claim 1, wherein the following equation:$n = {\frac{\left\lbrack {{Etching}\mspace{14mu} {rate}\mspace{14mu} {of}\mspace{14mu} {lowermost}\mspace{14mu} {layer}\mspace{14mu} {of}\mspace{14mu} {release}\mspace{14mu} {layer}} \right\rbrack}{\left\lbrack {{Etching}\mspace{14mu} {rate}\mspace{14mu} {of}\mspace{14mu} {uppermost}\mspace{14mu} {layer}\mspace{14mu} {of}\mspace{14mu} {organic}\mspace{14mu} {compound}\mspace{14mu} {layer}} \right\rbrack} > 10}$where n is a ratio of etching rates is established in the releaselayer-removing step.
 5. The method of manufacturing an organicelectroluminescence display device according to claim 1, furthercomprising the step of forming a layer containing an alkali metalcomponent on the organic compound layer after the release layer-removingstep.
 6. An electronic equipment, comprising: a display device; amemory; a CPU; and an operation portion, wherein the display devicecomprises an organic electroluminescence display device manufactured bythe method of manufacturing an organic electroluminescence displaydevice according to claim 1.